Protostars and Planets VI, Heidelberg, July 15-20, 2013

Poster 1B017

Wavelet-based cross-correlation analysis of the scaling in molecular clouds

Arshakian, Tigran (Universität zu Köln)
Ossenkopf, Volker (Universität zu Köln)

We develop a wavelet-based cross-correlation (WCC) method to study the correlation between structural changes in molecular clouds as a function of scale. The method compares a pair of maps observed in different tracers or at different velocity ranges. Advantages of the WCC method:  Allows to measure the correlation coefficient and structural offset between two maps as a function of scale.  Allows to weight individual pixels by their observational significance.  Is robust against the noise. Application of the WCC to simulated fBm (fractional Brownian motion) maps reveals that:  Cross-correlation coefficient can strongly depend on the scale.  Correlation coefficient and offset can be recovered robustly regardless of noise. Analysis of the G333 molecular line maps (13CO and C18O) shows:  A large scale gradient in the structural distribution. This could indicate a density structure where every core shows a low density tail towards the South-West mainly seen in 13CO. The WCC can be used to trace the correlated structural changes between different maps of a molecular cloud at scales representing the structural and physical importance such as chemical and phase transitions.

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